Process To Destroy Structures Composed Of Metallic Parts Fused/Attached To Asbestos

ABSTRACT

The present invention concerns processes to break up a structure made of metallic parts covered by asbestos. The process according to the present invention is essentially characterized by the fact that its implementation involves the following successive steps: cutting up of the structure by a laser beam or oxyacetylene torch to obtain fragments, coating of the cut fragments, and melting of the coated fragments in a closed furnace. Its application is especially for the destruction of asbestos covered metallic parts of large volume structures such as ships.

BACKGROUND OF THE INVENTION

We must remember that asbestos is found in nature as fibrous rocks. Asbestos is able to withstand high temperatures, up to 900 degrees Celsius. Asbestos has been used for about fifty years in the car industry, in particular for brake pads. It has been employed in the industry as a protection against high temperatures when welding glass or other materials. In the building industry asbestos has been used as a protection against fire and in the manufacture of cements (fibro cements etc.).

Since 1980, the use of asbestos has been forbidden in all its forms because fibers, the finest of which can have a diameter of 0.02 microns, penetrate into lung cells and cause, after a few years, cancer or other fatal or disabling lung diseases.

The current solution to destroy a structure covered by asbestos is to mechanically scrape asbestos from the structure. People doing this work must wear diving suits and the area where the operation takes place must be enclosed by walls such as a tent or any similar covering made of canvas or plastic. The atmosphere in this confined area must be continuously subject to suction.

This solution is not very efficient and remains dangerous. As a matter of fact, when there is no enclosure, in spite of the suction, no filter can really stop the smallest speck of dust. These particles have a life span of thirty thousand years in ambient air.

In addition, the problem of evacuating and stocking (for example, burying in the ground) the materials resulting from scraping arises. All the more so since scraping, being in itself an operation whose cost is prohibitive, the temptation to put these materials into unauthorized dumping grounds is very high.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a means to break up a structure composed of metallic parts containing asbestos. This process can be used in a distinctly useful way in the destruction of large volume structures such as ships or similar constructions.

More specifically, a purpose of the present invention is to implement a process to destroy a structure composed of metallic or similar parts covered by asbestos which can lead to very useful applications in the destruction of large volume structures such as ships or similar constructions. This process strongly overcomes the disadvantages, mentioned above, of the methods employed up till now.

More precisely, the present invention comprises a process to destroy a structure made of metallic parts covered by asbestos, which is characterized by the fact that its implementation involves the following successive steps:

-   -   Cutting of the structure with either a laser beam with suitable         power or to obtain fragments,     -   coating the fragments, and     -   melting the coated fragments in a closed furnace.

This process can also be characterized by the fact that the coating of the fragments can be accomplished by enclosing the fragments in a blister or something similar, or by spraying these fragments with a coat of varnish or something equivalent.

It may be desirable for the laser generator used to cut the structure to be a laser generator of from 5 to 50 kW, for example, with rotating fibers.

With a power of 5 kW, it is possible to cut a sheet of steel with a thickness of 25 millimeters at a cutting speed about 1 meter per minute.

It may be desirable for an isolation gas, such as compressed air or something similar, to be used to remove possible particles of steel and/or asbestos from the technicians and to facilitate the cutting.

With such a laser, asbestos near the cutting line is melted down, which transforms it to an inactive status.

As for the furnace used to obtain the melting of the coated fragments, it is recommended to use a plasma furnace, if possible equipped with a lock-chamber, preferably a slanted lock-chamber, to prevent the heat from sending particles outside when opening the chamber.

The temperature of the furnace is raised to between about 1400 to 4500 degrees Celsius which melts the fragments containing asbestos. Thus, steel ingots and inoffensive asbestos slag are obtained, all of which are usable for many applications.

The process according to the present invention has many advantage compared to similar processes of previous methods. More particularly, it avoids the prohibitive cost of asbestos suppression and waste removal. It allows the reuse of steel and asbestos slag and protects people and the environment. 

1. A process for destroying a structure made of metallic parts covered with asbestos, characterized by the fact that its implementation involves the following successive steps: cutting up the structure using a laser beam to obtain fragments, coating the fragments, and melting the coated fragments in a closed furnace.
 2. The process according to claim 1, wherein the coating of the fragments is obtained by enclosing the fragments in a blister or by spraying on these fragments a coat of varnish.
 3. The process according to claim 1, wherein the laser generator is a powerful laser, the power of which is between about 5 and 50 kWh.
 4. The process according to claim 1, wherein the furnace is a plasma furnace able to produce a temperature between about 1400 and 4500 degrees Celsius.
 5. The process according to claim 4, wherein the furnace is equipped with a lock-chamber to prevent heat from sending particles outside when opening a chamber of the furnace. 